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Artificial food colouring in packaged food tends to be listed on ingredient labels, but until now, the amount of food dye in brand name food products was a mystery.

But a new study, published in the journalClinical Pediatrics, looks at just how much artificial food dye is those popular products.

Laura Stevens is a research associate at Purdue University’s Nutrition Science department in West Lafayette, Ind. She said the data collected allows parents to look at what their kids eat and determine how much food dye they're ingesting.

Beverages are commonly coloured with food dye. Orange Crush was found to contain 33.6 mg per 8 oz. serving. (Facebook)

The research indicates a meal of two cups of Kraft Dinner,237 mL or eight ounces of Orange Crush and a bag of Skittles for dessert adds up to 102 milligrams of artificial food dye in one sitting.

Stevens said the data revealed surprises like lemon pudding tinted yellow with artificial dyes, and marshmallows and white icing tinted with multiple shades of food colouring.

"I thought it was interesting that pickles have yellow and blue dye to make them green, and I’ve looked through the pickles at our grocery store and haven’t found any that don’t contain those dyes," she said.

Vanilla frosting made by Duncan Hines lists Titanium Dioxide, Yellow 5, Red 40 as the colours used in this product. (Duncan Hines)

This issue has been looked at before, but supermarket shelves and buying habits have changed a lot since then.

"There’s been a lot of studies back in the '70s and '80s that used 26-27 milligrams of dyes and found that very few kids seemed to react to that amount," Stevens said.

"But when they increased it to 50-100 milligrams then a greater proportion of children reacted."

That initial amount of 26 milligrams used in the original studies seems pretty tame now, considering one serving of Kool-Aid’s Burst Cherry drink has twice that amount.

While nothing definitive has been found, artificial food dyes have long been studied for links to behavioural issues in kids.

"There were studies done in the U.K. recently that gave food dyes to a large group of healthy children, including ADHD kids," Stevens explained.

"And they found that not only did some of the ADHD kids react to the dyes, but also some of the children without ADHD reacted. And they reacted with more hyperactivity and inattention."

The results of that study were motivation enough for the European Union to start labelling foods with high amounts of food dye, linking them to potential behavioural problems in some kids.

The European Food Safety Agency said that though the effects of food dyes on behaviour were somewhat uncertain, the lack of nutritional benefits from the food colouring meant removing them wouldn't compromise a healthy diet.

And while no study has statistically proven the potential connection between food dye and behaviour problems, consumer pressure is forcing some companies to make changes.

Kraft has removed some dyes from its macaroni and cheese products, Pepperidge Farm switched to natural dyes for its coloured Goldfish crackers a few years ago and Frito-Lay has removed some artificial food dyes from several of their products.

While future studies are likely to continue looking for links between behaviour and artificial food dyes, Stevens said parents can try an elimination diet protocol with their own kids at home.

"All they have to do is avoid the foods that are coloured for a week or two. Then get the little bottles of red and green and yellow and blue food dye, put a few drops in a glass of water and ask their child to drink it. Then observe the behaviour."

Stevens said to watch for things like hyperactivity, runny nose, muscle aches, inattentiveness or higher levels of frustration.